From 80452ac0abc6494000a9bbad8d7dccfd72ea85f2 Mon Sep 17 00:00:00 2001
From: Egor Tensin <egor@tensin.name>
Date: Sat, 13 Jun 2026 15:42:15 +0200
Subject: aesxx: upgrade to std::string_view, std::format & <filesystem>

---
 aesxx/CMakeLists.txt                 |  3 +++
 aesxx/include/aesxx/aes.hpp          | 25 +++++++++++++------------
 aesxx/include/aesxx/api.hpp          | 15 +++------------
 aesxx/include/aesxx/box.hpp          | 29 +++++++----------------------
 aesxx/include/aesxx/debug.hpp        | 25 +++++++++----------------
 aesxx/include/aesxx/error.hpp        |  5 +++--
 aesxx/utils/CMakeLists.txt           |  3 +--
 aesxx/utils/block_cmd_parser.hpp     |  3 ++-
 aesxx/utils/block_dumper.hpp         | 14 ++++++++------
 aesxx/utils/block_input.hpp          |  5 +++--
 aesxx/utils/decrypt_block.cpp        |  7 ++++---
 aesxx/utils/decrypt_bmp.cpp          |  3 ++-
 aesxx/utils/decrypt_file.cpp         |  3 ++-
 aesxx/utils/encrypt_block.cpp        |  7 ++++---
 aesxx/utils/encrypt_bmp.cpp          |  3 ++-
 aesxx/utils/encrypt_file.cpp         |  3 ++-
 aesxx/utils/file_cmd_parser.hpp      |  3 ++-
 aesxx/utils/helpers/command_line.hpp | 14 ++++++++------
 18 files changed, 78 insertions(+), 92 deletions(-)

(limited to 'aesxx')

diff --git a/aesxx/CMakeLists.txt b/aesxx/CMakeLists.txt
index 378bad7..338ecef 100644
--- a/aesxx/CMakeLists.txt
+++ b/aesxx/CMakeLists.txt
@@ -1,3 +1,6 @@
+set(CMAKE_CXX_STANDARD 20)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
 find_package(Boost CONFIG REQUIRED)
 
 add_library(aesxx INTERFACE)
diff --git a/aesxx/include/aesxx/aes.hpp b/aesxx/include/aesxx/aes.hpp
index c3457c8..dedd366 100644
--- a/aesxx/include/aesxx/aes.hpp
+++ b/aesxx/include/aesxx/aes.hpp
@@ -14,6 +14,7 @@
 
 #include <cstddef>
 #include <string>
+#include <string_view>
 
 namespace aes {
 namespace aes128 {
@@ -37,8 +38,8 @@ inline std::size_t get_number_of_rounds<AES_AES128>() {
 }
 
 template <>
-inline void from_string<AES_AES128>(aes128::Block& dest, const char* src) {
-    aes_AES128_parse_block(&dest, src, ErrorDetailsThrowsInDestructor{});
+inline void from_string<AES_AES128>(aes128::Block& dest, std::string_view src) {
+    aes_AES128_parse_block(&dest, src.data(), ErrorDetailsThrowsInDestructor{});
 }
 
 template <>
@@ -56,8 +57,8 @@ inline std::string to_matrix_string<AES_AES128>(const aes128::Block& src) {
 }
 
 template <>
-inline void from_string<AES_AES128>(aes128::Key& dest, const char* src) {
-    aes_AES128_parse_key(&dest, src, ErrorDetailsThrowsInDestructor{});
+inline void from_string<AES_AES128>(aes128::Key& dest, std::string_view src) {
+    aes_AES128_parse_key(&dest, src.data(), ErrorDetailsThrowsInDestructor{});
 }
 
 template <>
@@ -110,8 +111,8 @@ inline std::size_t get_number_of_rounds<AES_AES192>() {
 }
 
 template <>
-inline void from_string<AES_AES192>(aes192::Block& dest, const char* src) {
-    aes_AES192_parse_block(&dest, src, ErrorDetailsThrowsInDestructor{});
+inline void from_string<AES_AES192>(aes192::Block& dest, std::string_view src) {
+    aes_AES192_parse_block(&dest, src.data(), ErrorDetailsThrowsInDestructor{});
 }
 
 template <>
@@ -129,8 +130,8 @@ inline std::string to_matrix_string<AES_AES192>(const aes192::Block& src) {
 }
 
 template <>
-inline void from_string<AES_AES192>(aes192::Key& dest, const char* src) {
-    aes_AES192_parse_key(&dest, src, ErrorDetailsThrowsInDestructor{});
+inline void from_string<AES_AES192>(aes192::Key& dest, std::string_view src) {
+    aes_AES192_parse_key(&dest, src.data(), ErrorDetailsThrowsInDestructor{});
 }
 
 template <>
@@ -183,8 +184,8 @@ inline std::size_t get_number_of_rounds<AES_AES256>() {
 }
 
 template <>
-inline void from_string<AES_AES256>(aes256::Block& dest, const char* src) {
-    aes_AES256_parse_block(&dest, src, ErrorDetailsThrowsInDestructor{});
+inline void from_string<AES_AES256>(aes256::Block& dest, std::string_view src) {
+    aes_AES256_parse_block(&dest, src.data(), ErrorDetailsThrowsInDestructor{});
 }
 
 template <>
@@ -202,8 +203,8 @@ inline std::string to_matrix_string<AES_AES256>(const aes256::Block& src) {
 }
 
 template <>
-inline void from_string<AES_AES256>(aes256::Key& dest, const char* src) {
-    aes_AES256_parse_key(&dest, src, ErrorDetailsThrowsInDestructor{});
+inline void from_string<AES_AES256>(aes256::Key& dest, std::string_view src) {
+    aes_AES256_parse_key(&dest, src.data(), ErrorDetailsThrowsInDestructor{});
 }
 
 template <>
diff --git a/aesxx/include/aesxx/api.hpp b/aesxx/include/aesxx/api.hpp
index 759ff0c..4c1c868 100644
--- a/aesxx/include/aesxx/api.hpp
+++ b/aesxx/include/aesxx/api.hpp
@@ -10,6 +10,7 @@
 
 #include <cstddef>
 #include <string>
+#include <string_view>
 #include <type_traits>
 
 namespace aes {
@@ -21,12 +22,7 @@ template <Algorithm algorithm>
 std::size_t get_number_of_rounds();
 
 template <Algorithm algorithm>
-void from_string(typename Types<algorithm>::Block&, const char*);
-
-template <Algorithm algorithm>
-void from_string(typename Types<algorithm>::Block& dest, const std::string& src) {
-    from_string<algorithm>(dest, src.c_str());
-}
+void from_string(typename Types<algorithm>::Block&, std::string_view);
 
 template <Algorithm algorithm>
 std::string to_string(const typename Types<algorithm>::Block&);
@@ -35,12 +31,7 @@ template <Algorithm algorithm>
 std::string to_matrix_string(const typename Types<algorithm>::Block&);
 
 template <Algorithm algorithm>
-void from_string(typename Types<algorithm>::Key&, const char*);
-
-template <Algorithm algorithm>
-void from_string(typename Types<algorithm>::Key& dest, const std::string& src) {
-    from_string<algorithm>(dest, src.c_str());
-}
+void from_string(typename Types<algorithm>::Key&, std::string_view);
 
 template <Algorithm algorithm>
 std::string to_string(const typename Types<algorithm>::Key&);
diff --git a/aesxx/include/aesxx/box.hpp b/aesxx/include/aesxx/box.hpp
index 540688b..fb42525 100644
--- a/aesxx/include/aesxx/box.hpp
+++ b/aesxx/include/aesxx/box.hpp
@@ -13,6 +13,7 @@
 
 #include <cstddef>
 #include <string>
+#include <string_view>
 #include <vector>
 
 namespace aes {
@@ -34,20 +35,12 @@ public:
         return reinterpret_cast<const char*>(&str);
     }
 
-    static void parse_block(Block& dest, Algorithm algorithm, const char* src) {
-        aes_box_parse_block(&dest, algorithm, src, ErrorDetailsThrowsInDestructor{});
+    static void parse_block(Block& dest, Algorithm algorithm, std::string_view src) {
+        aes_box_parse_block(&dest, algorithm, src.data(), ErrorDetailsThrowsInDestructor{});
     }
 
-    static void parse_block(Block& dest, Algorithm algorithm, const std::string& src) {
-        parse_block(dest, algorithm, src.c_str());
-    }
-
-    static void parse_key(Key& dest, Algorithm algorithm, const char* src) {
-        aes_box_parse_key(&dest, algorithm, src, ErrorDetailsThrowsInDestructor{});
-    }
-
-    static void parse_key(Key& dest, Algorithm algorithm, const std::string& src) {
-        parse_key(dest, algorithm, src.c_str());
+    static void parse_key(Key& dest, Algorithm algorithm, std::string_view src) {
+        aes_box_parse_key(&dest, algorithm, src.data(), ErrorDetailsThrowsInDestructor{});
     }
 
     Box(Algorithm algorithm, const Key& key) : algorithm{algorithm}, mode{AES_ECB} {
@@ -115,22 +108,14 @@ public:
         return format_key(src, get_algorithm());
     }
 
-    void parse_block(Block& dest, const char* src) {
+    void parse_block(Block& dest, std::string_view src) {
         parse_block(dest, get_algorithm(), src);
     }
 
-    void parse_block(Block& dest, const std::string& src) {
-        parse_block(dest, src.c_str());
-    }
-
-    void parse_key(Key& dest, const char* src) {
+    void parse_key(Key& dest, std::string_view src) {
         parse_key(dest, get_algorithm(), src);
     }
 
-    void parse_key(Key& dest, const std::string& src) {
-        parse_key(dest, src.c_str());
-    }
-
     Algorithm get_algorithm() const {
         return algorithm;
     }
diff --git a/aesxx/include/aesxx/debug.hpp b/aesxx/include/aesxx/debug.hpp
index d54605d..13ea898 100644
--- a/aesxx/include/aesxx/debug.hpp
+++ b/aesxx/include/aesxx/debug.hpp
@@ -13,8 +13,10 @@
 #endif
 
 #include <cstddef>
+#include <format>
 #include <sstream>
 #include <string>
+#include <string_view>
 
 namespace aes {
 namespace aux {
@@ -34,37 +36,28 @@ public:
 private:
     template <typename T>
     static std::string put_between_brackets(const T& x) {
-        std::ostringstream oss;
-        oss << "[" << x << "]";
-        return oss.str();
-    }
-
-    template <typename T>
-    static std::string stringify(const T& x) {
-        std::ostringstream oss;
-        oss << x;
-        return oss.str();
+        return std::format("[{}]", x);
     }
 
     static std::string format_address_fallback(const void* addr) {
         return put_between_brackets(addr);
     }
 
-    static std::string format_module(const std::string& module_name, const void* offset = nullptr) {
+    static std::string format_module(std::string_view module_name, const void* offset = nullptr) {
         if (offset == nullptr)
             return put_between_brackets(module_name);
         else
-            return put_between_brackets(module_name + "+" + stringify(offset));
+            return put_between_brackets(std::format("{}+{}", module_name, offset));
     }
 
-    static std::string format_symbol(const std::string& symbol_name, const void* offset = nullptr) {
+    static std::string format_symbol(std::string_view symbol_name, const void* offset = nullptr) {
         return format_module(symbol_name, offset);
     }
 
-    static std::string format_symbol(const std::string& module_name,
-                                     const std::string& symbol_name,
+    static std::string format_symbol(std::string_view module_name,
+                                     std::string_view symbol_name,
                                      const void* offset = nullptr) {
-        return format_symbol(module_name + "!" + symbol_name, offset);
+        return format_symbol(std::format("{}!{}", module_name, symbol_name), offset);
     }
 
 #ifdef WIN32
diff --git a/aesxx/include/aesxx/error.hpp b/aesxx/include/aesxx/error.hpp
index e5c5803..72a50b3 100644
--- a/aesxx/include/aesxx/error.hpp
+++ b/aesxx/include/aesxx/error.hpp
@@ -14,6 +14,7 @@
 #include <algorithm>
 #include <cstdlib>
 #include <cstring>
+#include <format>
 #include <functional>
 #include <ostream>
 #include <stdexcept>
@@ -60,10 +61,10 @@ private:
 };
 
 inline std::ostream& operator<<(std::ostream& os, const Error& error) {
-    os << "AES error: " << error.what() << '\n';
+    os << std::format("AES error: {}\n", error.what());
     os << "Call stack:\n";
     error.for_each_addr([&os](const void* addr, const std::string& name) {
-        os << '\t' << addr << ' ' << name << '\n';
+        os << std::format("\t{} {}\n", addr, name);
     });
     return os;
 }
diff --git a/aesxx/utils/CMakeLists.txt b/aesxx/utils/CMakeLists.txt
index 9ee06d0..de6c206 100644
--- a/aesxx/utils/CMakeLists.txt
+++ b/aesxx/utils/CMakeLists.txt
@@ -1,4 +1,4 @@
-find_package(Boost CONFIG REQUIRED COMPONENTS filesystem program_options)
+find_package(Boost CONFIG REQUIRED COMPONENTS program_options)
 
 function(add_util name src)
     set(target "util_${name}")
@@ -6,7 +6,6 @@ function(add_util name src)
     target_link_libraries("${target}" PRIVATE
         aesxx
         Boost::disable_autolinking
-        Boost::filesystem
         Boost::program_options)
     set_target_properties("${target}" PROPERTIES OUTPUT_NAME "${name}")
     install(TARGETS "${target}" RUNTIME DESTINATION bin)
diff --git a/aesxx/utils/block_cmd_parser.hpp b/aesxx/utils/block_cmd_parser.hpp
index 3ae0eac..c179556 100644
--- a/aesxx/utils/block_cmd_parser.hpp
+++ b/aesxx/utils/block_cmd_parser.hpp
@@ -16,6 +16,7 @@
 #include <deque>
 #include <iterator>
 #include <string>
+#include <string_view>
 #include <utility>
 #include <vector>
 
@@ -29,7 +30,7 @@ public:
 
     std::vector<Input> inputs;
 
-    explicit BlockSettings(const std::string& argv0) : SettingsParser{argv0} {
+    explicit BlockSettings(std::string_view argv0) : SettingsParser{argv0} {
         visible.add_options()(
             "verbose,v", boost::program_options::bool_switch(&verbose), "enable verbose output");
         visible.add_options()("algorithm,a",
diff --git a/aesxx/utils/block_dumper.hpp b/aesxx/utils/block_dumper.hpp
index 226ba20..c725670 100644
--- a/aesxx/utils/block_dumper.hpp
+++ b/aesxx/utils/block_dumper.hpp
@@ -8,13 +8,15 @@
 #include <aesxx/all.hpp>
 
 #include <cstdlib>
+#include <format>
 #include <iostream>
+#include <string_view>
 #include <type_traits>
 
 template <aes::Algorithm algorithm>
-void dump_block(const char* header, const typename aes::Types<algorithm>::Block& block) {
-    std::cout << header << ": " << aes::to_string<algorithm>(block) << "\n";
-    std::cout << aes::to_matrix_string<algorithm>(block) << "\n";
+void dump_block(std::string_view header, const typename aes::Types<algorithm>::Block& block) {
+    std::cout << std::format("{}: {}\n", header, aes::to_string<algorithm>(block));
+    std::cout << std::format("{}\n", aes::to_matrix_string<algorithm>(block));
 }
 
 template <aes::Algorithm algorithm>
@@ -24,7 +26,7 @@ void dump_plaintext(const typename aes::Types<algorithm>::Block& block) {
 
 template <aes::Algorithm algorithm>
 void dump_key(const typename aes::Types<algorithm>::Key& key) {
-    std::cout << "Key: " << aes::to_string<algorithm>(key) << "\n\n";
+    std::cout << std::format("Key: {}\n\n", aes::to_string<algorithm>(key));
 }
 
 template <aes::Algorithm algorithm>
@@ -40,9 +42,9 @@ void dump_iv(const typename aes::Types<algorithm>::Block& iv) {
 template <aes::Algorithm algorithm>
 void dump_round_keys(const char* header,
                      const typename aes::Types<algorithm>::RoundKeys& round_keys) {
-    std::cout << header << ":\n";
+    std::cout << std::format("{}:\n", header);
     for (std::size_t i = 0; i < aes::get_number_of_rounds<algorithm>(); ++i)
-        std::cout << "\t[" << i << "]: " << aes::to_string<algorithm>(round_keys.keys[i]) << "\n";
+        std::cout << std::format("\t[{}]: {}\n", i, aes::to_string<algorithm>(round_keys.keys[i]));
     std::cout << "\n";
 }
 
diff --git a/aesxx/utils/block_input.hpp b/aesxx/utils/block_input.hpp
index 1dd3f70..042a680 100644
--- a/aesxx/utils/block_input.hpp
+++ b/aesxx/utils/block_input.hpp
@@ -6,15 +6,16 @@
 #pragma once
 
 #include <string>
+#include <string_view>
 #include <utility>
 #include <vector>
 
 class Input {
 public:
-    Input(const std::string& key, const std::string& iv, std::vector<std::string>&& blocks)
+    Input(std::string_view key, std::string_view iv, std::vector<std::string>&& blocks)
         : key{key}, iv{iv}, blocks{std::move(blocks)} {}
 
-    Input(const std::string& key, std::vector<std::string>&& blocks)
+    Input(std::string key, std::vector<std::string>&& blocks)
         : key{key}, blocks{std::move(blocks)} {}
 
     const std::string key;
diff --git a/aesxx/utils/decrypt_block.cpp b/aesxx/utils/decrypt_block.cpp
index 42e496e..d432e31 100644
--- a/aesxx/utils/decrypt_block.cpp
+++ b/aesxx/utils/decrypt_block.cpp
@@ -12,6 +12,7 @@
 #include <boost/program_options.hpp>
 
 #include <exception>
+#include <format>
 #include <iostream>
 #include <stdexcept>
 #include <string>
@@ -48,7 +49,7 @@ void decrypt_with_mode(const Input& input, bool verbose = false) {
             dump_plaintext<algorithm>(plaintext);
             dump_next_iv<algorithm, mode>(decrypt);
         } else {
-            std::cout << aes::to_string<algorithm>(plaintext) << '\n';
+            std::cout << std::format("{}\n", aes::to_string<algorithm>(plaintext));
         }
     }
 }
@@ -112,7 +113,7 @@ void decrypt_using_particular_box(aes::Box& box, const std::vector<std::string>&
 
         aes::Box::Block plaintext;
         box.decrypt_block(ciphertext, plaintext);
-        std::cout << box.format_block(plaintext) << '\n';
+        std::cout << std::format("{}\n", box.format_block(plaintext));
     }
 }
 
@@ -161,7 +162,7 @@ int main(int argc, char** argv) {
         std::cerr << e;
         return 1;
     } catch (const std::exception& e) {
-        std::cerr << e.what() << "\n";
+        std::cerr << std::format("{}\n", e.what());
         return 1;
     }
     return 0;
diff --git a/aesxx/utils/decrypt_bmp.cpp b/aesxx/utils/decrypt_bmp.cpp
index 86f6b7d..397ec02 100644
--- a/aesxx/utils/decrypt_bmp.cpp
+++ b/aesxx/utils/decrypt_bmp.cpp
@@ -14,6 +14,7 @@
 #include <windows.h>
 
 #include <exception>
+#include <format>
 #include <iostream>
 #include <string>
 
@@ -69,7 +70,7 @@ int main(int argc, char** argv) {
         std::cerr << e;
         return 1;
     } catch (const std::exception& e) {
-        std::cerr << e.what() << "\n";
+        std::cerr << std::format("{}\n", e.what());
         return 1;
     }
     return 0;
diff --git a/aesxx/utils/decrypt_file.cpp b/aesxx/utils/decrypt_file.cpp
index 727362c..192f1f6 100644
--- a/aesxx/utils/decrypt_file.cpp
+++ b/aesxx/utils/decrypt_file.cpp
@@ -11,6 +11,7 @@
 #include <boost/program_options.hpp>
 
 #include <exception>
+#include <format>
 #include <iostream>
 #include <string>
 #include <vector>
@@ -67,7 +68,7 @@ int main(int argc, char** argv) {
         std::cerr << e;
         return 1;
     } catch (const std::exception& e) {
-        std::cerr << e.what() << "\n";
+        std::cerr << std::format("{}\n", e.what());
         return 1;
     }
     return 0;
diff --git a/aesxx/utils/encrypt_block.cpp b/aesxx/utils/encrypt_block.cpp
index b6bdca9..e132256 100644
--- a/aesxx/utils/encrypt_block.cpp
+++ b/aesxx/utils/encrypt_block.cpp
@@ -12,6 +12,7 @@
 #include <boost/program_options.hpp>
 
 #include <exception>
+#include <format>
 #include <iostream>
 #include <stdexcept>
 #include <string>
@@ -48,7 +49,7 @@ void encrypt_with_mode(const Input& input, bool verbose = false) {
             dump_ciphertext<algorithm>(ciphertext);
             dump_next_iv<algorithm, mode>(encrypt);
         } else {
-            std::cout << aes::to_string<algorithm>(ciphertext) << '\n';
+            std::cout << std::format("{}\n", aes::to_string<algorithm>(ciphertext));
         }
     }
 }
@@ -113,7 +114,7 @@ void encrypt_using_particular_box(aes::Box& box,
 
         aes::Box::Block ciphertext;
         box.encrypt_block(plaintext, ciphertext);
-        std::cout << box.format_block(ciphertext) << '\n';
+        std::cout << std::format("{}\n", box.format_block(ciphertext));
     }
 }
 
@@ -162,7 +163,7 @@ int main(int argc, char** argv) {
         std::cerr << e;
         return 1;
     } catch (const std::exception& e) {
-        std::cerr << e.what() << "\n";
+        std::cerr << std::format("{}\n", e.what());
         return 1;
     }
     return 0;
diff --git a/aesxx/utils/encrypt_bmp.cpp b/aesxx/utils/encrypt_bmp.cpp
index 01f3a78..5b74fb9 100644
--- a/aesxx/utils/encrypt_bmp.cpp
+++ b/aesxx/utils/encrypt_bmp.cpp
@@ -12,6 +12,7 @@
 #include <boost/program_options.hpp>
 
 #include <exception>
+#include <format>
 #include <iostream>
 #include <string>
 
@@ -67,7 +68,7 @@ int main(int argc, char** argv) {
         std::cerr << e;
         return 1;
     } catch (const std::exception& e) {
-        std::cerr << e.what() << "\n";
+        std::cerr << std::format("{}\n", e.what());
         return 1;
     }
     return 0;
diff --git a/aesxx/utils/encrypt_file.cpp b/aesxx/utils/encrypt_file.cpp
index 4a774fd..2862bfb 100644
--- a/aesxx/utils/encrypt_file.cpp
+++ b/aesxx/utils/encrypt_file.cpp
@@ -11,6 +11,7 @@
 #include <boost/program_options.hpp>
 
 #include <exception>
+#include <format>
 #include <iostream>
 #include <string>
 #include <vector>
@@ -67,7 +68,7 @@ int main(int argc, char** argv) {
         std::cerr << e;
         return 1;
     } catch (const std::exception& e) {
-        std::cerr << e.what() << "\n";
+        std::cerr << std::format("{}\n", e.what());
         return 1;
     }
     return 0;
diff --git a/aesxx/utils/file_cmd_parser.hpp b/aesxx/utils/file_cmd_parser.hpp
index 4a504c8..2389d41 100644
--- a/aesxx/utils/file_cmd_parser.hpp
+++ b/aesxx/utils/file_cmd_parser.hpp
@@ -15,6 +15,7 @@
 
 #include <ostream>
 #include <string>
+#include <string_view>
 #include <utility>
 
 class FileSettings : public command_line::SettingsParser {
@@ -27,7 +28,7 @@ public:
     std::string key;
     std::string iv;
 
-    explicit FileSettings(const std::string& argv0) : SettingsParser{argv0} {
+    explicit FileSettings(std::string_view argv0) : SettingsParser{argv0} {
         visible.add_options()("algorithm,a",
                               boost::program_options::value<aes::Algorithm>(&algorithm)
                                   ->required()
diff --git a/aesxx/utils/helpers/command_line.hpp b/aesxx/utils/helpers/command_line.hpp
index 9a2da05..cc05a6a 100644
--- a/aesxx/utils/helpers/command_line.hpp
+++ b/aesxx/utils/helpers/command_line.hpp
@@ -5,19 +5,21 @@
 
 #pragma once
 
-#include <boost/filesystem.hpp>
 #include <boost/program_options.hpp>
 
 #include <exception>
+#include <filesystem>
+#include <format>
 #include <iostream>
 #include <ostream>
 #include <string>
+#include <string_view>
 
 namespace command_line {
 
 class SettingsParser {
 public:
-    explicit SettingsParser(const std::string& argv0) : prog_name{extract_filename(argv0)} {
+    explicit SettingsParser(std::string_view argv0) : prog_name{extract_filename(argv0)} {
         visible.add_options()("help,h", "show this message and exit");
     }
 
@@ -49,7 +51,7 @@ public:
     }
 
     void usage_error(const std::exception& e) const {
-        std::cerr << "usage error: " << e.what() << '\n';
+        std::cerr << std::format("usage error: {}\n", e.what());
         std::cerr << *this;
     }
 
@@ -59,15 +61,15 @@ protected:
     boost::program_options::positional_options_description positional;
 
 private:
-    static std::string extract_filename(const std::string& path) {
-        return boost::filesystem::path{path}.filename().string();
+    static std::string extract_filename(std::string_view path) {
+        return std::filesystem::path{path}.filename().string();
     }
 
     const std::string prog_name;
 
     friend std::ostream& operator<<(std::ostream& os, const SettingsParser& parser) {
         const auto short_descr = parser.get_short_description();
-        os << "usage: " << parser.prog_name << ' ' << short_descr << '\n';
+        os << std::format("usage: {} {}\n", parser.prog_name, short_descr);
         os << parser.visible;
         return os;
     }
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